August 25, 2026, Mountain View, CA -- Planets form from disks of gas and dust around young stars, but the gas needed for growth does not last forever. New observations from NASA’s James Webb Space Telescope (JWST) now offer a new view of how this gas escapes and how the process changes as young planetary systems develop.
The research, led by Naman Bajaj from the University of Arizona and co-authored by SETI Institute scientist Uma Gorti , looked at 72 young, Sun-like stars and their protoplanetary disks. This is one of the largest planet-formation studies using JWST. The findings show that different types of winds are more important at different stages in a planetary system’s early life.
The results have been published in The Astronomical Journal ( https://doi.org/10.3847/1538-3881/ae9089 )
“ What is exciting about this study is that we can now see, across a large sample of young systems, how the mechanisms that remove gas from planet-forming disks change with time. Disk dispersal sets a fundamental clock for planet formation: once the gas is gone, the opportunity to build gas-rich planets is essentially over,” said Gorti.
Today, our solar system is about 4.5 billion years old and is mostly empty space. In its first few million years, though, the Sun was surrounded by a thick protoplanetary disk with about 100 times more gas than dust. Most of that gas eventually vanished.
Figuring out how and when this happens is important because the gas in these disks is the main ingredient for giant planets like Jupiter and Saturn. If the gas goes away too soon, these planets might not have enough time to build up their thick atmospheres.
To study this process, Bajaj and his team used archival data from JWST’s Mid-Infrared Instrument (MIRI). Each of the 72 systems represents a different stage in the early life of a planetary system. When combined, these observations are like frames in a movie, helping researchers piece together how disk dispersal changes over time.
In 2020, LPL professor Ilaria Pascucci, second author of the paper and Bajaj's advisor, led a team that conducted a similar study to understand how jets and winds evolve. At that time, pre-JWST, they couldn't observe molecular hydrogen directly, but they predicted the existence of molecular winds and that these winds could be massive enough to block X-ray photons at earlier ages. With this new study, by tracing molecular hydrogen directly, Bajaj's team also confirmed these predictions with the JWST images.
The team focused on two signs of escaping gas: molecular hydrogen, which is the most common molecule in protoplanetary disks, and ionized neon. Thanks to JWST’s sensitivity and sharp vision, the researchers could tell the difference between broad molecular hydrogen winds and the jets and winds marked by neon.
In younger systems that are still sending material onto their stars, the observations reveal strong jets and broad winds made of both molecular and atomic gas. These outflows match what scientists expect from winds driven by magnetic fields running through the disk. Gas can travel along these magnetic field lines, moving away from the disk and taking mass and angular momentum with it.
As these systems age and less material falls onto the star, the jets get weaker and the winds become mostly atomic. At this point, high-energy radiation from the star can reach through the thinning material and heat the disk gas until it escapes. This process is called photoevaporation.
Gorti has spent decades studying how protoplanetary disks evolve and disperse, including how ultraviolet and X-ray radiation from young stars can drive photoevaporative winds. The new JWST observations connect that theoretical work with what astronomers can now see across dozens of planetary systems, showing how photoevaporation becomes increasingly important as disks age and magnetically driven jets and winds weaken.
The results show that no single process controls how a planet-forming disk disappears. Instead, planetary systems seem to move from an early stage with strong, magnetically driven jets and winds to a later stage where atomic winds, including photoevaporative winds, play a bigger role.
This shift directly affects how planets form.
“Planet formation is therefore a race against time,” Bajaj said. “Gas giants like Jupiter must assemble their massive atmospheres while the disk is still substantial enough to supply them, before winds and jets carry that raw material away into space.”
The study found extended emissions from molecular hydrogen and ionized neon in 66 out of the 72 disks. The researchers saw conical molecular hydrogen winds in 46 systems and fast-moving neon jets in 40. Every system with a neon jet also had signs of a wind traced by molecular hydrogen or oxygen.
These findings build on earlier work by the same team. In 2024, Bajaj, Gorti, and their colleagues used JWST to capture an image of gas being carried away from the planet-forming disk around the young star T Cha.
That study showed JWST can directly study disk dispersal in a single system. The new research takes this approach to dozens of young stars, showing how the mix of jets, molecular winds, and atomic winds shifts as planetary systems grow older.
The next goal is to find out exactly how much gas these winds remove over time and where in the disk the escaping material comes from. These measurements could help scientists learn not just how fast the planet-forming window closes, but also where different kinds of planets can form before their gas runs out.
The paper, “JWST/MIRI Reveals the Evolution from Molecular to Atomic Disk Winds,” is led by Naman S. Bajaj of the University of Arizona. Co-authors are Ilaria Pascucci, Sylvie Cabrit, Suzan Edwards, Gabriele Cugno, Andrew D. Sellek, Joan R. Najita, Ke Zhang, Richard Alexander, Gregory J. Herczeg, Uma Gorti of the SETI Institute and NASA Ames Research Center , Sophie C. Clark and Tracy L. Beck.
About the SETI Institute
Founded in 1984, the SETI Institute is a non-profit, multi-disciplinary research and education organization whose mission is to lead humanity’s quest to understand the origins and prevalence of life and intelligence in the Universe and to share that knowledge with the world. Our research encompasses the physical and biological sciences and leverages expertise in data analytics, machine learning and advanced signal detection technologies. The SETI Institute is a distinguished research partner for industry, academia and government agencies, including NASA and NSF.
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The Astronomical Journal
JWST/MIRI Reveals the Evolution from Molecular to Atomic Disk Winds
25-Aug-2026